The present invention relates to measurement, data acquisition, and control, and particularly to measurement devices with adaptive interfaces and modular signal conditioning and conversion devices which convey interface information.
Scientists and engineers often use measurement or instrumentation systems to perform a variety of functions, including laboratory research, process monitoring and control, data logging, analytical chemistry, test and analysis of physical phenomena, and control of mechanical or electrical machinery, to name a few examples. An instrumentation system typically includes transducers and other detecting means for providing xe2x80x9cfieldxe2x80x9d electrical signals representing a process, physical phenomena, equipment being monitored or measured, etc. For example, detectors and/or sensors are used to sense the on/off state of power circuits, proximity switches, pushbutton switches, thermostats, relays or even the presence of positive or negative digital logic-level signals. The instrumentation system typically also includes interface hardware for receiving the measured field signals and providing them to a processing system, such as a personal
Often, the field signals may be coupled to high common-mode voltages, ground loops, or voltage spikes that often occur in industrial or research environments which could damage the computer system. In that case, the instrumentation system typically includes isolation circuitry such as opto-couplers for eliminating ground-loop problems and isolating the computer from potentially damaging voltages. Input modules are typically provided for conditioning the raw field voltage signals by amplifying, isolating, filtering or otherwise converting the signals to the appropriate digital signals for the computer system. As one example, the digital signals are then provided to a plug-in data acquisition (DAQ) input/output (I/O) board, or a computer-based instrument which is plugged into one of the I/O slots of a computer system. Generally, the computer system has an I/O bus and connectors or slots for receiving I/O boards. Various computer systems and I/O buses may be used to implement a processing system.
Typical DAQ, measurement, and control modules include circuitry or components to provide a standard interface to external systems, such as PCI or PXI boards. The inclusion of these standard interface components on each module may be expensive, and may also substantially increase the size of a given module. Additionally, when multiple modules are used in a single system, such as a PXI based system fielding multiple sensors, the inclusion of PXI interface circuitry on each sensor is redundant and inefficient. Finally, if multiple communication interfaces are desired for the modules, the expense and size of the modules may increase dramatically with the inclusion of each additional interface card.
Therefore, improved measurement systems are desired which reduce cost and enhance efficiency and flexibility.
Various embodiments of a system and method for measurement, DAQ, and control operations are described. The system may use small form-factor measurement modules in conjunction with a re-configurable carrier unit, sensors and a computer system to provide modular, efficient, cost-effective measurement solutions. In one embodiment, the measurement module is operable to communicate interface information to the carrier, which in turn informs the computer system how to program the carrier to implement the communicated interface, i.e., how to xe2x80x9ctalkxe2x80x9d to the measurement module. In another embodiment, the carrier itself may include a processor and memory which receives the interface information from the module and programs reconfigurable hardware on the carrier to implement the interface.
This xe2x80x9cadaptive interfacexe2x80x9d approach allows the measurement module to include only components necessary for providing the required functionality, i.e., the measurement module does not have to include hardware and software implementing standard interfaces for communication with external systems. Said another way, much of the interface responsibilities of the measurement module are assumed by the carrier, which itself is programmed by the computer system, thus the measurement module may be smaller and cheaper than typical functional modules. In the preferred embodiment, the measurement module has a small form factor. For example, in one embodiment, the measurement module may have dimensions less than or equal to approximately 1 inch by 2 inches by 3 inches. In one embodiment, the measurement module may have dimensions of approximately 0.2 inches by 1 inch by 1 inch or more. Thus, in a preferred embodiment, the measurement module has a compact form factor which may enable deployment in a variety of devices or carriers with minimal space requirements.
A typical measurement system using this approach includes a computer system coupled to a measurement or data acquisition (DAQ) device, which may include a carrier and one or more measurement modules. As used herein, the term xe2x80x9cmeasurement devicexe2x80x9d is intended to include any of various types of devices that are operable to acquire and/or store data, and which may optionally be further operable to analyze or process the acquired or stored data. Examples of a measurement device include various types of instruments, such as oscilloscopes, multimeters a data acquisition device or card, a device external to a computer that operates similarly to a data acquisition card, a smart sensor, one or more DAQ or measurement modules in a chassis, and other similar types of devices. The computer system may couple to the measurement device through a serial bus, such as a USB (Universal Serial Bus), or any other medium including Ethernet, wireless media such as IEEE 802.11 (Wireless Ethernet) Bluetooth, a network, such as a Control Area Network (CAN) or the Internet, serial or parallel buses, or any other transmission means.
The host computer may comprise a CPU, a display screen, memory, and one or more input devices such as a mouse or keyboard, and may operate with the measurement device to analyze or measure data from the sensor/measurement device or to control the sensor and/or device. Alternatively, the computer may be used only to configure or program the measurement device, i.e., the carrier, as described below.
In one embodiment, the measurement module may include measurement circuitry which is operable to perform signal conditioning and/or signal conversion, e.g., a signal conditioner and/or a signal converter, such as an analog to digital converter (ADC) or a digital to analog converter. The measurement module may also include interface circuitry which is operable to provide an interface for the measurement circuitry, and which may also be operable to communicate an interface protocol to the carrier unit describing the interface, as mentioned above. The measurement module may also include additional transmission lines and/or buses for operation, e.g., a trigger line coupled to the ADC which may receive trigger signals from an external source, such as the computer system, and a power line for supplying power to the measurement module.
The measurement module may be further operable to couple to a sensor or actuator. The sensor may receive signals from a device or unit under test (UUT) and may send sensor signals to the measurement module for one or more of signal conditioning and signal conversion. For example, the sensor may measure a phenomenon, such as temperature, pressure, voltage, current, or any other phenomenon, and send signals to the measurement module. The signal conditioner comprised in the measurement module may then perform signal conditioning on the signals, where signal conditioning may include one or more of protection, isolation, filtering, amplification, and excitation, or other signal conditioning operations. The conditioned signals may then be processed by the signal converter, also comprised in the measurement module, which may be operable to perform one or more of analog to digital (AID) conversion and digital to analog (D/A) conversion of the signal, depending on whether the signal is analog or digital. The conditioned, converted signals may then be transmitted by the interface circuitry to the carrier using the specified interface protocol. In other words, the measurement module may transmit the conditioned, converted signals to the carrier over the serial transmission medium SPI. The carrier may then further analyze the signals or transmit the signals to an external system, such as computer system.
In a preferred embodiment, the carrier includes a functional unit, e.g., a processor and memory or a programmable hardware element, which may be programmed by the computer system, or in other embodiments, by a processor and memory on the carrier. As used herein, the term xe2x80x9cprocessorxe2x80x9d is intended to include any of types of processors, CPUs, microcontrollers, or other devices capable of executing software instructions. As used herein, the term xe2x80x9cprogrammable hardware elementxe2x80x9d is intended to include various types of programmable hardware, reconfigurable hardware, programmable logic, or field-programmable devices (FPDs), such as one or more FPGAs (Field Programmable Gate Arrays), or one or more PLDs (Programmable Logic Devices), such as one or more Simple PLDs (SPLDs) or one or more Complex PLDs (CPLDs), or other types of programmable hardware.
As mentioned above, the carrier unit is operable to receive interface protocol information from the measurement module specifying how to operate or interface with the measurement module. In one embodiment, the carrier unit may then communicate the interface protocol information to the computer system. Alternatively, the measurement module may communicate the interface protocol information directly to the computer system. Based on the interface protocol information, the computer system may program or configure the functional unit on the carrier unit to implement the interface as specified by the measurement module. In other words, the measurement module may tell the carrier how to xe2x80x9ctalkxe2x80x9d with it, and the carrier may then tell the computer system how to program the carrier to communicate with the measurement module accordingly (or the measurement module may tell the computer system directly how to program the carrier). The computer system may then program the carrier (i.e., the carrier""s functional unit), thereby implementing the interface specified in the interface protocol information communicated by the measurement module.
As noted above, in another embodiment, the carrier unit may be operable to receive the interface protocol information from the measurement module, and a processor and memory on the carrier unit may then program or configure the functional unit on the carrier unit to implement the interface as specified by the measurement module. In other words, the measurement module may communicate its interface protocol to the carrier, and the carrier may program itself (i.e., a processor/memory on the carrier may program a programmable hardware element) to communicate with the measurement module accordingly, thereby implementing the interface specified in the interface protocol information communicated by the measurement module.
This process may be referred to as initialization of the measurement module/carrier. The configured carrier and the measurement module may then be operable to perform measurement and data acquisition operations using the sensor and/or the computer system. In other words, the measurement module and the programmed carrier unit together may be operable to perform a measurement device (including a DAQ device), and/or a control device.
In one embodiment, the computer system may also store a program implementing one or more measurement functions, i.e., a measurement program. The measurement program may be a graphical program implementing the one or more measurement functions. The computer system may be operable to execute the measurement program to perform the one or more measurement functions, preferably in conjunction with operation of the carrier and/or measurement module, including analysis of data or signals received from the carrier, control of carrier and/or measurement module operations, and user interface functions, among others.
In another embodiment, the computer system may be operable to deploy the measurement program onto the functional unit of the carrier unit. In other words, in addition to, or instead of, programming the carrier unit to implement the interface, the computer system may download the measurement program onto the functional unit of the carrier, after which the carrier may be operable to execute the measurement program to perform the one or more measurement functions, preferably in conjunction with operation of the measurement module, and possibly the computer system. The configured carrier and the measurement module may then be operable to perform measurement and data acquisition operations using the sensor and/or the computer system.
In one embodiment, the carrier may also process and/or analyze the signals, and send the results of the processing or analysis to the computer system for storage and/or further analysis.
In various embodiments, the measurement module may also include a functional unit, e.g., a processor (or microprocessor) and memory, or a programmable hardware element (e.g., an FPGA), which may be operable to implement the module side of the specified interface and/or control module operations. Thus, the measurement module may include measurement circuitry, e.g., the signal conditioner and/or the signal converter (e.g., ADC or DAC), which may be operable to perform one or more of signal conditioning and signal conversion, as well as interface circuitry (including the functional unit) which is operable to provide an interface for the measurement circuitry. More specifically, the functional unit of the measurement module may retrieve the interface protocol information from memory and communicate the interface protocol information to the carrier.
In one embodiment, the measurement module may include signal input terminals for receiving analog inputs, e.g., from a sensor, and for optionally receiving a Transducer Electronic Data Sheet (TEDS) describing the functionality of the transducer (e.g., sensor) in machine-readable form. The measurement module may further include isolation circuitry which may be operable to protect the components of the measurement module from spurious signals, signal noise, harmful voltage and/or current surges, impedance mismatches, and the like.
The measurement module may also include terminals for communicating with external systems such as the computer system, including SPI, trigger line(s), power and ground lines, among others.
In one embodiment, the measurement module may be in the form of a measurement cartridge and the carrier in the form of a cartridge carrier which is operable to receive one or more of the measurement cartridges. For example, the carrier unit may comprise a chassis, a backplane comprised in the chassis providing for electrical communication, and one or more slots comprised in the chassis. Each of the one or more slots may include a connector that is coupled to the backplane, where each of the one or more slots may be adapted for receiving a measurement module. Thus, the carrier may host a plurality of measurement cartridges, each of which may provide measurement and/or control functionality for a measurement or control operation or task. The carrier may be operable to communicate with each measurement cartridge (i.e., module) and be programmed or configured (e.g., by the computer system or by a processor on the carrier) to implement the respective interface of each measurement cartridge. In this manner a suite of sensors may be fielded, each of which feeds signals to a respective measurement cartridge which in turn communicates through a respective interface (protocol) with the cartridge carrier. The cartridge carrier may in turn couple to a computer system. Thus, the carrier may support a heterogeneous plurality of interfaces without having to include a heterogeneous set of interface hardware components.
In a preferred embodiment, the measurement modules (or cartridges) may be easily removed, added, and replaced. In other words, measurement modules may be exchanged to change the configuration or capabilities of the measurement system. In one embodiment, the measurement module may be replaced without powering down the measurement system, i.e., the measurement module may be xe2x80x9chot-pluggedxe2x80x9d into the carrier, where the measurement module may communicate the interface protocol information to the carrier upon attachment, and the carrier is programmed in response, as described above. In another embodiment, the measurement module and/or carrier may require a reboot or reset after attachment to perform the described initialization. Thus, the interface circuitry (i.e., the measurement module) may be operable to communicate the interface protocol to the carrier unit upon one or more of attachment of the measurement module to the carrier unit, reset of the measurement module, reset of the carrier unit, reboot of the measurement module, and reboot of the carrier unit.
In one embodiment, the carrier may comprise a PXI card, i.e., may be implemented on a PXI card. The PXI card may be operable to plug into a PXI chassis or a suitably equipped computer system, and may implement the carrier functionality described above, i.e., the PXI card may include (in addition to PXI interface circuitry, memory, etc.) a functional unit which is programmable or configurable to implement an interface based on interface protocol information transmitted from a coupled measurement module, as described above. It should be noted that other card based implementations besides the PXI card implementation are also contemplated, for example, PCI, VXI, Infiniband, or other protocols or platforms may be used to implement a carrier, the PXI card embodiment being but one example.
In one embodiment, the carrier unit may comprise or be coupled to a Personal Digital Assistant (PDA). Thus the PDA may comprise the carrier unit and include one or more slots for measurement modules. Alternatively, the carrier unit may be in the form of an optionally detachable carrier module, which may in turn couple to a measurement module. The measurement module may in turn be operable to couple to a sensor or actuator, as described above. In one embodiment, the PDA may be operable to program the carrier (i.e., the carrier unit""s functional unit) with the interface protocol information provided by the measurement module, as described in detail above, and may be further operable to provide functionality related to a measurement, and/or control task or operation. In another embodiment, the PDA may be used as an interface to another computer system. For example, a suitably equipped PDA may provide wireless communication for the carrier/measurement module.
In one embodiment, the measurement system may include a measurement module coupled to a xe2x80x9cRIOxe2x80x9d Reconfigurable I/O carrier, also referred to as a generalized carrier. As used herein, the term xe2x80x9cRIOxe2x80x9d carrier refers to a carrier which includes reconfigurable hardware which is configurable with respective interface protocols for one or more cartridges. In other words, a RIO carrier with multiple cartridge slots may be configured with multiple interfaces for inserted cartridges, such that each cartridge""s interface is implemented by the RIO carrier. For example, if three cartridges with three different respective interfaces are inserted in three slots of the RIO carrier, then the RIO carrier may be configured to implement the three interfaces. Similarly, if multiple cartridges are sequentially inserted into and removed from a particular slot, the RIO carrier may be configured respectively for each cartridge, i.e., sequentially. The RIO carrier may further be operable to couple to any of various products or platforms.
In one embodiment, a channel or bus may be provided by the RIO carrier for each cartridge/interface protocol. In other words, each slot may have an associated dedicated bus for that slot, with a corresponding portion of the RIO carrier""s reconfigurable hardware configurable to implement the interface for a cartridge inserted into the slot. In another embodiment, the RIO carrier may include a shared bus or backplane common to a plurality of the slots, where inserted cartridges may communicate through the common bus or backplane with the reconfigurable hardware of the RIO carrier in accordance with the respective interface protocols implemented on the reconfigurable hardware.
In yet another embodiment, the RIO carrier may be configurable to include not only the adaptive interface functionality described above, but may also include or may be configured to include, one or more measurement and/or control functions. For example, the carrier may perform all or a portion of timing, triggering, and synchronization functions for inserted cartridges or modules.
In one embodiment, the RIO carrier may include the carrier components/functionality described above, and may also include a register set, through which communication with the products/platforms may be effected. In various embodiments, the RIO carrier may provide additional functions which may include I/O scanning, timing and triggering, power-on states, logic, digital I/O timing/counting, data transfer and support for parallel and scanned backplanes, among others. Various products and platforms may provide means for the carrier to communicate with external systems. For example, an Application Programming Interface (API) may allow external systems to read and/or write to the registers in the register set to communicate and/or control the measurement system. For another example, a processor, e.g., a micro-controller, and a network interface card may couple the registers to a network through which communications with external systems may be facilitated.
In one embodiment, RIO based systems, i.e., a RIO carrier, may be extended with external I/O expansion, i.e., with additional I/O connections for coupling to a plurality of measurement modules. A RIO cartridge or card may provide connectors for analog I/O and/or digital I/O. The digital I/O may be coupled to an I/O expansion device, such as a breakout backplane, which may provide connectivity for a plurality of measurement module cards or cartridges, and may thereby be operable to facilitate external, synchronized, and conditioned I/O for the measurement system.
In another embodiment, the RIO card or device may couple to an addressable backplane, for example, through an SPI with slot select capabilities, and which may provide a plurality of individually addressable slots for a plurality of measurement modules or cartridges, which may each be individually targeted for communication by the carrier. Additionally, the addressable backplane may be expandable, i.e., additional addressable backplanes may be coupled to the addressable backplane to provide additional slots for additional measurement modules.
In yet another embodiment, the RIO card or device may couple to a xe2x80x9cmeasurement module in the cablexe2x80x9d, where a measurement module may be comprised in a cable connector. In other words, the features of a measurement module, as described above, may be included in one or both connectors of a cable which may be coupled to the RIO device or to a sensor/actuator, as desired.
Thus, the use of measurement modules in combination with a variety of platforms, carrier units, and computer systems provides a broad range of approaches for efficient and affordable measurement systems, including established platforms such as PCI/PXI and FieldPoint, generalized carriers such as RIO, new USB/Ethernet devices, and small networked measurement nodes (e.g., smart sensors) for highly distributed measurement systems. These systems may provide for efficient, low-cost, modular, data acquisition, control, and integrated signal conditioning and conversion, as well as interfaces to sensors and actuators, including plug and play (PnP) sensors, and may do so using a small form factor.